Data backup and replication systems create copies of enterprise data at local or remote sites. Some conventional backup and replication systems operate by tracking I/O write commands from physical or virtual servers to storage devices such as storage area network (SAN), network attached storage (NAS) and direct attached storage (DAS). Other conventional systems operate by creating clones or snapshots of enterprise data. Such systems generally save only the last snapshot or clone on disk, or several last snapshots or clones. Recent systems provide continuous data protection (CDP) by journaling write commands so as so provide any point in time data recovery.
Conventional systems limit CDP capability based on disk space available to maintain a journal. Service providers define their objectives and service level agreements (SLAB) in terms of time. For CDP, the SLA generally relates to the window of time history that can be recovered.
As such, a drawback with conventional data backup and replication systems is that an IT professional must be able to correctly estimate the disk space that will be required in order to maintain a desired time frame, and reserve this amount of disk space. Generally, the estimation is inaccurate and the reserved disk space is wasted. Specifically, during off-peak periods, the reserved disk space is unused, and during peak periods the disk space is not able to accommodate all of the changes and maintain the entire SLA history window.
Today, enterprise infrastructures are evolving as pools of resources for on-demand use, instead of reserved pre-allocated resources. Thus it would be of advantage to provide a data backup and replication system that is flexibly adaptable to journal size requirements.